The information in this article applies to:
SUMMARY
The TvwState.exe sample demonstrates how to simulate a multiple-selection
TreeView control. The Windows 95 TreeView control does not support multiple
selection. If you want a multiple-selection TreeView, you can use state
images to simulate it in your application.
MORE INFORMATIONThe following file is available for download from the Microsoft
Download Center. Click the file name below to download the file: TvwState.exeFor more information about how to download files from the Microsoft Download Center, please visit the Download Center at the following Web address http://www.microsoft.com/downloads/search.aspand then click How to use the Microsoft Download Center. The multiple-selection TreeView control simulation is implemented by setting the state image list of the TreeView control to an image list that contains the checked and unchecked checkbox bitmaps. This image list is set by using the TVM_SETIMAGELIST message with lParam == TVSIL_STATE (see InitImageList in TVWSTATE.C). A TreeView control can have two image lists, a normal image list and a state image list. In the TreeView, the display order from left to right is: the expansion button, the state image (if present), the normal image (if present), and then the item text. When processing the WM_NOTIFY message where (LPNMHDR)lParam->code == NM_CLICK (see MsgNotifyTreeView in TVWSTATE.C), the code checks to see if the user clicked the left mouse button in the checkbox. If this is the case, the state image index of the item is retrieved, the index is toggled between the checked and unchecked image list items, and then the new index is saved. The state image index identifies which member of the state image list should be displayed. The state image index is stored in bits 12-16 of the item state value. Either TVIS_STATEIMAGEMASK or TVIS_USERMASK can be used to mask off the lower bits. To access just the state image index, use a statement similar to this:
The INDEXTOSTATEIMAGEMASK macro offsets a value to the correct bits for the state image index. This is accomplished by shifting the given value left 12 places. If the desired state image index is 1, the state can be set using a statement similar to this:
This sample can also be modified to implement selection methods similar to
those of an extended-selection listbox where the user uses the SHIFT key to
select a range of items and/or the CTRL key to select or clear individual
items.
Additional query words:
Keywords : kbfile kbsample kbCtrl kbNTOS351 kbNTOS400 kbWinOS2000 kbSDKWin32 kbTreeView kbGrpUser kbWinOS95 kbWinOS98 |
Last Reviewed: February 2, 2000 © 2000 Microsoft Corporation. All rights reserved. Terms of Use. |